Technological Development and Medical Productivity: The Diffusion of Angioplasty in New York State

A puzzling feature of many medical innovations is that they simultaneously appear to reduce unit costs and increase total costs. We consider this phenomenon by examining the diffusion of percutaneous transluminal coronary angioplasty (PTCA) -- a treatment for coronary artery disease -- over the past two decades. We find that growth in the use of PTCA led to higher total costs despite its lower unit cost. Over the two decades following PTCA's introduction, however, we find that the magnitude of this increase was reduced by between 10% and 20% due to the substitution of PTCA for CABG. In addition, the increased use of PTCA appears to be a productivity improvement. PTCAs that substitute for CABG cost less and have the same or better outcomes, while PTCAs that replace medical management appear to improve health by enough to justify the cost.

A trapped mercury 199 ion frequency standard

Mercury 199 ions confined in an RF quadrupole trap and optically pumped by mercury 202 ion resonance light are investigated as the basis for a high performance frequency standard with commercial possibilities. Results achieved and estimates of the potential performance of such a standard are given

The Determinants of Mortality

Mortality rates have fallen dramatically over time, starting in a few countries in the 18th century, and continuing to fall today. In just the past century, life expectancy has increased by over 30 years. At the same time, mortality rates remain much higher in poor countries, with a difference in life expectancy between rich and poor countries of also about 30 years. This difference persists despite the remarkable progress in health improvement in the last half century, at least until the HIV/AIDS pandemic. In both the time-series and the cross-section data, there is a strong correlation between income per capita and mortality rates, a correlation that also exists within countries, where richer, better-educated people live longer. We review the determinants of these patterns: over history, over countries, and across groups within countries. While there is no consensus about the causal mechanisms, we tentatively identify the application of scientific advance and technical progress (some of which is induced by income and facilitated by education) as the ultimate determinant of health. Such an explanation allows a consistent interpretation of the historical, cross-country, and within-country evidence. We downplay direct causal mechanisms running from income to health.

The Role of Information in Medical Markets: An Analysis of Publicly Reported Outcomes in Cardiac Surgery

During the past two decades, several public and private organizations have initiated programs to report publicly on the quality of medical care provided by specific hospitals and physicians. These programs have sparked broad debate among economists and policy makers concerning whether, and to what extent, they have improved or harmed medical productivity. We take advantage of a cross-sectional time series of different hospitals to address two fundamental questions about quality reporting. First, we examine whether report cards affect the distribution of patients across hospitals. Second, we determine whether report cards lead to improved medical quality among hospitals identified as particularly bad or good performers. Our data are from the longest-standing effort to measure and report health care quality the Cardiac Surgery Reporting System (CSRS) in New York State. Using data for 1991 through 1999, we find that CSRS affected both the volume of cases and future quality at hospitals identified as poor performers. Poor performing hospitals lost relatively healthy patients to competing facilities and experienced subsequent improvements in their performance as measured by risk-adjusted mortality.

Input Constraints and the Efficiency of Entry: Lessons from Cardiac Surgery

Prior studies suggest that, with elastically supplied inputs, free entry may lead to an inefficiently high number of firms in equilibrium. Under input scarcity, however, the welfare loss from free entry is reduced. Further, free entry may increase use of high-quality inputs, as oligopolistic firms underuse these inputs when entry is constrained. We assess these predictions by examining how the 1996 repeal of certificate-of-need (CON) legislation in Pennsylvania affected the market for cardiac surgery in the state. We show that entry led to a redistribution of surgeries to higher-quality surgeons and that this entry was approximately welfare neutral.

Testing Alternative Theories of Gravity using LISA

We investigate the possible bounds which could be placed on alternative theories of gravity using gravitational wave detection from inspiralling compact binaries with the proposed LISA space interferometer. Specifically, we estimate lower bounds on the coupling parameter \omega of scalar-tensor theories of the Brans-Dicke type and on the Compton wavelength of the graviton \lambda_g in hypothetical massive graviton theories. In these theories, modifications of the gravitational radiation damping formulae or of the propagation of the waves translate into a change in the phase evolution of the observed gravitational waveform. We obtain the bounds through the technique of matched filtering, employing the LISA Sensitivity Curve Generator (SCG), available online. For a neutron star inspiralling into a 10^3 M_sun black hole in the Virgo Cluster, in a two-year integration, we find a lower bound \omega > 3 * 10^5. For lower-mass black holes, the bound could be as large as 2 * 10^6. The bound is independent of LISA arm length, but is inversely proportional to the LISA position noise error. Lower bounds on the graviton Compton wavelength ranging from 10^15 km to 5 * 10^16 km can be obtained from one-year observations of massive binary black hole inspirals at cosmological distances (3 Gpc), for masses ranging from 10^4 to 10^7 M_sun. For the highest-mass systems (10^7 M_sun), the bound is proportional to (LISA arm length)^{1/2} and to (LISA acceleration noise)^{-1/2}. For the others, the bound is independent of these parameters because of the dominance of white-dwarf confusion noise in the relevant part of the frequency spectrum. These bounds improve and extend earlier work which used analytic formulae for the noise curves.Comment: 16 pages, 9 figures, submitted to Classical & Quantum Gravit

LISA detections of massive black hole inspirals: parameter extraction errors due to inaccurate template waveforms

The planned Laser Interferometer Space Antenna (LISA) is expected to detect the inspiral and merger of massive black hole binaries (MBHBs) at z <~ 5 with signal-to-noise ratios (SNRs) of hundreds to thousands. Because of these high SNRs, and because these SNRs accrete over periods of weeks to months, it should be possible to extract the physical parameters of these systems with high accuracy; for instance, for a ~ 10^6 Msun MBHBs at z = 1 it should be possible to determine the two masses to ~ 0.1% and the sky location to ~ 1 degree. However, those are just the errors due to noise: there will be additional "theoretical" errors due to inaccuracies in our best model waveforms, which are still only approximate. The goal of this paper is to estimate the typical magnitude of these theoretical errors. We develop mathematical tools for this purpose, and apply them to a somewhat simplified version of the MBHB problem, in which we consider just the inspiral part of the waveform and neglect spin-induced precession, eccentricity, and PN amplitude corrections. For this simplified version, we estimate that theoretical uncertainties in sky position will typically be ~ 1 degree, i.e., comparable to the statistical uncertainty. For the mass and spin parameters, our results suggest that while theoretical errors will be rather small absolutely, they could still dominate over statistical errors (by roughly an order of magnitude) for the strongest sources. The tools developed here should be useful for estimating the magnitude of theoretical errors in many other problems in gravitational-wave astronomy.Comment: RevTeX4, 16 pages, 2 EPS figures. Corrected typos, clarified statement

Angular Resolution of the LISA Gravitational Wave Detector

We calculate the angular resolution of the planned LISA detector, a space-based laser interferometer for measuring low-frequency gravitational waves from galactic and extragalactic sources. LISA is not a pointed instrument; it is an all-sky monitor with a quadrupolar beam pattern. LISA will measure simultaneously both polarization components of incoming gravitational waves, so the data will consist of two time series. All physical properties of the source, including its position, must be extracted from these time series. LISA's angular resolution is therefore not a fixed quantity, but rather depends on the type of signal and on how much other information must be extracted. Information about the source position will be encoded in the measured signal in three ways: 1) through the relative amplitudes and phases of the two polarization components, 2) through the periodic Doppler shift imposed on the signal by the detector's motion around the Sun, and 3) through the further modulation of the signal caused by the detector's time-varying orientation. We derive the basic formulae required to calculate the LISA's angular resolution $\Delta \Omega_S$ for a given source. We then evaluate $\Delta \Omega_S$ for two sources of particular interest: monchromatic sources and mergers of supermassive black holes. For these two types of sources, we calculate (in the high signal-to-noise approximation) the full variance-covariance matrix, which gives the accuracy to which all source parameters can be measured. Since our results on LISA's angular resolution depend mainly on gross features of the detector geometry, orbit, and noise curve, we expect these results to be fairly insensitive to modest changes in detector design that may occur between now and launch. We also expect that our calculations could be easily modified to apply to a modified design.Comment: 15 pages, 5 figures, RevTex 3.0 fil